Methods for depositing low k and low wet etch rate dielectric thin films

ABSTRACT

Methods for the formation of SiCN, SiCO and SiCON films comprising cyclical exposure of a substrate surface to a silicon-containing gas, a carbon-containing gas and a plasma. Some embodiments further comprise the addition of an oxidizing agent prior to at least the plasma exposure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/156,257, filed May 2, 2015, the entire disclosure of which is herebyincorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to methods of depositing thinfilms. In particular, the disclosure relates to atomic layer depositionprocesses for the deposition of films comprising SiCN, SiCO and/orSiCON.

BACKGROUND

Silicon nitride films may play an important role in the manufacture oftransistors, as a nitride spacer, or in memory, as the floating gate. Inorder to deposit these films with good step coverage over nanoscale,high-aspect ratio structures, a film deposition called Atomic LayerDeposition (ALD) is needed. ALD is the deposition of a film bysequentially pulsing two or more precursors separated by an inert purge.This allows the film growth to proceed layer by layer and is limited bythe surface active sites. Film growth in this manner allows forthickness control over complex structures, including re-entrancefeatures.

Dielectric thin films with low dielectric constants (low k) and low wetetch rate (in diluted HF solution) properties, such as SiCN or SiCON,can be used as spacer materials in front end processes in thesemiconductor industry. Most thin film properties cannot meet practicalrequirements due to poor film composition control, such as hydrogencontamination and/or different bonding states of carbon in the film.Poor conformality of the film deposited on 3D trenches is also known.Accordingly, there is a need in the art for low k and low wet etch rateSiCN, SiCO and SiCON films.

SUMMARY

One or more embodiments of the disclosure are directed to processingmethods. At least a portion of a substrate surface is exposed to asilicon-containing precursor to form a first silicon-containing film.The first silicon-containing film is exposed to a carbon-containingprecursor to form a second silicon-containing film. The secondsilicon-containing film comprises carbon. The second silicon-containingfilm is exposed to a plasma to form a silicon-carbon film.

Additional embodiments of the disclosure are directed to processingmethods comprising exposing a substrate surface to at least twodeposition cycles. Each deposition cycle comprises exposing at least aportion of the substrate surface to a silicon-containing precursor toform a first silicon-containing film. The silicon-containing film isexposed to a carbon-containing precursor consisting essentially ofcarbon and nitrogen atoms to form a second silicon-containing film. Thesecond silicon-containing film is exposed to a plasma to form a siliconcarbonitride film.

Further embodiments of the disclosure are directed to processing methodscomprising placing a substrate having a substrate surface into aprocessing chamber. The processing chamber comprises a plurality ofsections, where each section is separated from adjacent sections by agas curtain. At least a portion of the substrate surface is exposed to afirst process condition in a first section of the processing chamber.The first process condition comprises a silicon-containing precursor toform a first silicon-containing film. The substrate surface is laterallymoved through a gas curtain to a second section of the processingchamber. The first silicon-containing film is exposed to acarbon-containing precursor to form a second silicon-containing film.The carbon-containing precursor consists essentially of carbon andnitrogen atoms to form a second silicon-containing film. The substratesurface with the second silicon-containing film is laterally movedthrough at least one gas curtain to a third section or fourth section ofthe processing chamber. The second silicon-containing film is exposed toa plasma comprising an inert gas and, optionally, one or more ofhydrogen, nitrogen and oxygen containing species to form a siliconcarbonitride or silicon oxycarbonitride film. The substrate surface islaterally moved from the third section or fourth section of theprocessing chamber through a gas curtain. The exposure to the firstsection, second section and third section or fourth section includinglateral movement of the substrate surface is repeated to form a siliconcarbonitride or silicon oxycarbonitride film of a predeterminedthickness.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows a cross-sectional view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 2 shows a partial perspective view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 3 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a portion of a wedge shaped gasdistribution assembly for use in a batch processing chamber inaccordance with one or more embodiment of the disclosure; and

FIG. 5 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways. It is also to be understood that thecomplexes and ligands of the present disclosure may be illustratedherein using structural formulas which have a particularstereochemistry. These illustrations are intended as examples only andare not to be construed as limiting the disclosed structure to anyparticular stereochemistry. Rather, the illustrated structures areintended to encompass all such complexes and ligands having theindicated chemical formula.

The inventors have surprisingly found that a spatial atomic layerdeposition process can form low k and low wet etch rate (WER) SiCN, SiCOand SiCON films. As used in this specification and the appended claims,use of the term SiCN only means that the film has silicon, carbon andnitrogen atoms and does not imply stoichiometric amounts. The use ofSiCO and SiCON also refer to the atomic components, not a stoichiometricamount. The films may have other atoms present unless otherwiseindicated. Typically, the other atoms present are not found in aquantity that would affect the film properties. Use of the term“consisting essentially of”, when describing a precursor or filmcomposition refers only to the atomic percentage of silicon, carbon,oxygen and nitrogen atoms. For example, a precursor consistingessentially of carbon and nitrogen atoms means that there aresubstantially no oxygen atoms. The precursor may have other elements,like hydrogen. The use of “substantially no oxygen atoms”, and the like,mean that oxygen atoms are not present in an amount greater than about 2atomic %, 1 atomic %, 0.5 atomic % or 0.1 atomic %.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, silicon nitride, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present disclosure, any of the film processingsteps disclosed may also be performed on an underlayer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such underlayer as the contextindicates. Thus for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

According to one or more embodiments, the method uses an atomic layerdeposition (ALD) process. In such embodiments, the substrate surface isexposed to the precursors (or reactive gases) sequentially orsubstantially sequentially. As used herein throughout the specification,“substantially sequentially” means that a majority of the duration of aprecursor exposure does not overlap with the exposure to a co-reagent,although there may be some overlap. As used in this specification andthe appended claims, the terms “precursor”, “reactant”, “reactive gas”and the like are used interchangeably to refer to any gaseous speciesthat can react with the substrate surface.

One or more embodiments of the disclosure are directed to processingmethods comprising sequentially exposing a substrate surface to asilicon-containing precursor and a carbon-containing precursor and aplasma. The sequential exposure of the silicon-containing precursor, thecarbon-containing precursor and the plasma forms a silicon-carbon film.As used in this regard, a “silicon-carbon film” refers to a filmcomprising silicon and carbon atoms, but is not limited to only siliconand carbon. In some embodiments, at least a portion of a substratesurface is exposed to a silicon-containing precursor to form a firstsilicon-containing film. The first silicon-containing film is thenexposed to a carbon-containing precursor to form a secondsilicon-containing film which comprises silicon and carbon. Withoutbeing bound by any particular theory of operation, it is believed thatthe film has unwanted terminations, such as chloride terminated or OHterminated components. The subsequent exposure to the plasma causes thefilm to cross-link and remove most, if not all, of these unwantedterminations.

The silicon-containing precursor can include any suitable siliconprecursor that can react with the substrate surface. Thesilicon-containing precursor can be halogenated or non-halogenated. Ahalogenated precursor means that at least one halogen atom is bound to asilicon atom. Suitable silicon halide include, but are not limited to,SiCl₄, monochlorosilane, dichlorosilane, trichlorosilane, silane,disilane, organosilicates, aminosilanes and organosilanes. In someembodiments, the silicon-containing precursor consists essentially ofsilicon halide. As used in this regard, “consists essentially of siliconhalide” means that the gas flow contains substantially only siliconhalide as a surface active component. Other non-reactive gases, forexample, carrier gases, can be included.

The carbon-containing precursor can include any suitablecarbon-containing species that can react with the substrate surface, orthe silicon-containing film on the surface. Suitable examples include,but are not limited to, carbon tetrachloride, carbon dioxide, alkanes,ethylene diamine and acetylene. In some embodiments, thecarbon-containing precursor comprises a compound having carbon andnitrogen atoms, for example, ethylene diamine.

In one or more embodiments, the carbon-containing precursor consistsessentially of carbon and nitrogen atoms, meaning that there issubstantially no oxygen atoms present in the precursor. In someembodiments, the carbon-containing precursor consists essentially ofethylene diamine. For example, such a precursor might be useful for thedeposition of a SiCN film. In some embodiments, the carbon-containingprecursor comprises one or more of an alkylamine, diamine, polyamineand/or a cyclic amine. The amines can be primary, secondary, tertiary orheterocyclic.

In one or more embodiments, the carbon-containing precursor comprises acompound having carbon and oxygen atoms. For example, such a precursormight be useful for the deposition of SiCO films. In some embodiments,the carbon-containing precursor comprises substantially no carbon atomsor the precursor consists essentially of carbon and oxygen atoms,meaning that there are substantially no nitrogen atoms. For example, thecarbon-containing precursor can include one or more of CO₂, an alcoholand/or an ether.

In some embodiments, the carbon-containing precursor comprises carbon,oxygen and nitrogen atoms. For example, such a precursor might be usefulin the deposition of SiCON films. In one or more embodiments, thecarbon-containing precursor comprises one or more of analkylamino-alcohol or a mixture of compounds having carbon and nitrogenatoms and/or carbon and oxygen atoms.

The plasma can be any suitable plasma species. In some embodiments, theplasma comprises at least one inert species. For example, an argonplasma. In some embodiments, the plasma further comprises a species thatreacts with the film, such as hydrogen or oxygen. In some embodiments,the plasma comprises at least one inert species and an oxygen speciesand the silicon-carbon film further comprises oxygen. In one or moreembodiments, the plasma comprises at least one inert species and anitrogen-containing precursor and the silicon-carbon film furthercomprises nitrogen.

In some embodiments, the plasma comprises one or more of helium, neon,argon or krypton. In one or more embodiments, the plasma furthercomprises one or more of hydrogen, ammonia and/or nitrogen. For example,the plasma may comprise an argon/nitrogen, argon/hydrogen and/orargon/nitrogen/ammonia mixture. The inventors have surprisingly foundthat the composition of the plasma, e.g., the species and relativeconcentrations, can impact the film properties.

The power of the plasma also has a surprising effect on the filmproperties. Any suitable plasma frequency or power can be used. In someembodiments, the plasma power is in the range of about 25 watts to about300 watts, or in the range of about 50 watts to about 200 watts, orabout 200 watts, about 100 watts, or about 50 watts.

In some embodiments, the first silicon-containing film and/or the secondsilicon-containing film is exposed to an oxygen source prior to exposureto the plasma. For example, after exposing the first silicon-containingfilm to ethylene diamine, the film can be exposed to water vapor toincorporate oxygen into the film. This can be done during the plasma orprior to plasma exposure. Suitable oxygen sources include but are notlimited to oxygen, carbon dioxide, water and ozone.

The processing method can be performed at any suitable temperature. Insome embodiments, all of the processing portions are, independently,within the range of about 200° C. and about 650° C. It has been foundthat the silicon-carbon films can be deposited at lower temperature thanexpected. In some embodiments, all of the processing conditions areindependently, less than or equal to about 500° C., 450° C., 400° C. or350° C.

The silicon-carbon film formed has properties that make films with lowwet etch rates, low dielectric constants, and high thermal stabilityand/or form films with good conformality. In some embodiments, a siliconcarbonitride film is formed and has a wet etch rate ratio (WERR) indilute HF of less than about 0.5, or about 0.4, or about 0.3, or about0.2, or about 0.1, or about 0.05. The wet etch rate ratio is measuredrelative to a thermal silicon oxide film using dilute HF (e.g., 1:100HF).

The silicon-carbon films formed had excellent growth rates. In someembodiments, the silicon nitride film has a growth rate greater than orequal to about 0.2 Å/cycle, or greater than or equal to about 0.25Å/cycle, or greater than or equal to about 0.3 Å/cycle, or greater thanor equal to about 0.35 Å/cycle, or greater than or equal to about 0.4Å/cycle, or greater than or equal to about 0.45 Å/cycle.

Some embodiments of the disclosure are directed to silicon nitride filmdeposition using a batch processing chamber, also referred to as aspatial ALD chamber. FIG. 1 shows a cross-section of a processingchamber 100 including a gas distribution assembly 120, also referred toas injectors or an injector assembly, and a susceptor assembly 140. Thegas distribution assembly 120 is any type of gas delivery device used ina processing chamber. The gas distribution assembly 120 includes a frontsurface 121 which faces the susceptor assembly 140. The front surface121 can have any number or variety of openings to deliver a flow ofgases toward the susceptor assembly 140. The gas distribution assembly120 also includes an outer edge 124 which in the embodiments shown, issubstantially round.

The specific type of gas distribution assembly 120 used can varydepending on the particular process being used. Embodiments of thedisclosure can be used with any type of processing system where the gapbetween the susceptor and the gas distribution assembly is controlled.While various types of gas distribution assemblies can be employed(e.g., showerheads), embodiments of the disclosure may be particularlyuseful with spatial ALD gas distribution assemblies which have aplurality of substantially parallel gas channels. As used in thisspecification and the appended claims, the term “substantially parallel”means that the elongate axis of the gas channels extend in the samegeneral direction. There can be slight imperfections in the parallelismof the gas channels. The plurality of substantially parallel gaschannels can include at least one first reactive gas A channel, at leastone second reactive gas B channel, at least one purge gas P channeland/or at least one vacuum V channel. The gases flowing from the firstreactive gas A channel(s), the second reactive gas B channel(s) and thepurge gas P channel(s) are directed toward the top surface of the wafer.Some of the gas flow moves horizontally across the surface of the waferand out of the processing region through the purge gas P channel(s). Asubstrate moving from one end of the gas distribution assembly to theother end will be exposed to each of the process gases in turn, forminga layer on the substrate surface.

In some embodiments, the gas distribution assembly 120 is a rigidstationary body made of a single injector unit. In one or moreembodiments, the gas distribution assembly 120 is made up of a pluralityof individual sectors (e.g., injector units 122), as shown in FIG. 2.Either a single piece body or a multi-sector body can be used with thevarious embodiments of the disclosure described.

The susceptor assembly 140 is positioned beneath the gas distributionassembly 120. The susceptor assembly 140 includes a top surface 141 andat least one recess 142 in the top surface 141. The susceptor assembly140 also has a bottom surface 143 and an edge 144. The recess 142 can beany suitable shape and size depending on the shape and size of thesubstrates 60 being processed. In the embodiment shown in FIG. 1, therecess 142 has a flat bottom to support the bottom of the wafer;however, the bottom of the recess can vary. In some embodiments, therecess has step regions around the outer peripheral edge of the recesswhich are sized to support the outer peripheral edge of the wafer. Theamount of the outer peripheral edge of the wafer that is supported bythe steps can vary depending on, for example, the thickness of the waferand the presence of features already present on the back side of thewafer.

In some embodiments, as shown in FIG. 1, the recess 142 in the topsurface 141 of the susceptor assembly 140 is sized so that a substrate60 supported in the recess 142 has a top surface 61 substantiallycoplanar with the top surface 141 of the susceptor 140. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within ±0.15 mm, ±0.10 mm or ±0.05 mm.

The susceptor assembly 140 of FIG. 1 includes a support post 160 whichis capable of lifting, lowering and rotating the susceptor assembly 140.The susceptor assembly may include a heater, or gas lines, or electricalcomponents within the center of the support post 160. The support post160 may be the primary means of increasing or decreasing the gap betweenthe susceptor assembly 140 and the gas distribution assembly 120, movingthe susceptor assembly 140 into proper position. The susceptor assembly140 may also include fine tuning actuators 162 which can makemicro-adjustments to susceptor assembly 140 to create a predeterminedgap 170 between the susceptor assembly 140 and the gas distributionassembly 120. In some embodiments, the gap 170 distance is in the rangeof about 0.1 mm to about 5.0 mm, or in the range of about 0.1 mm toabout 3.0 mm, or in the range of about 0.1 mm to about 2.0 mm, or in therange of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mmto about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or inthe range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, orin the range of about 0.8 mm to about 1.2 mm, or in the range of about0.9 mm to about 1.1 mm, or about 1 mm.

The processing chamber 100 shown in the Figures is a carousel-typechamber in which the susceptor assembly 140 can hold a plurality ofsubstrates 60. As shown in FIG. 2, the gas distribution assembly 120 mayinclude a plurality of separate injector units 122, each injector unit122 being capable of depositing a film on the wafer, as the wafer ismoved beneath the injector unit. Two pie-shaped injector units 122 areshown positioned on approximately opposite sides of and above thesusceptor assembly 140. This number of injector units 122 is shown forillustrative purposes only. It will be understood that more or lessinjector units 122 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 122 to form a shapeconforming to the shape of the susceptor assembly 140. In someembodiments, each of the individual pie-shaped injector units 122 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 122. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 140and gas distribution assembly 120 to load/unload substrates 60.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 3, the processing chamber100 has four gas injector assemblies and four substrates 60. At theoutset of processing, the substrates 60 can be positioned between theinjector assemblies 30. Rotating 17 the susceptor assembly 140 by 45°will result in each substrate 60 which is between injector assemblies120 to be moved to an injector assembly 120 for film deposition, asillustrated by the dotted circle under the injector assemblies 120. Anadditional 45° rotation would move the substrates 60 away from theinjector assemblies 30. With spatial ALD injectors, a film is depositedon the wafer during movement of the wafer relative to the injectorassembly. In some embodiments, the susceptor assembly 140 is rotated inincrements that prevent the substrates 60 from stopping beneath theinjector assemblies 120. The number of substrates 60 and gasdistribution assemblies 120 can be the same or different. In someembodiments, there is the same number of wafers being processed as thereare gas distribution assemblies. In one or more embodiments, the numberof wafers being processed are fraction of or an integer multiple of thenumber of gas distribution assemblies. For example, if there are fourgas distribution assemblies, there are 4× wafers being processed, wherex is an integer value greater than or equal to one.

The processing chamber 100 shown in FIG. 3 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 120. In the embodiment shown, there arefour gas distribution assemblies (also called injector assemblies 30)evenly spaced about the processing chamber 100. The processing chamber100 shown is octagonal; however, those skilled in the art willunderstand that this is one possible shape and should not be taken aslimiting the scope of the disclosure. The gas distribution assemblies120 shown are trapezoidal, but can be a single circular component ormade up of a plurality of pie-shaped segments, like that shown in FIG.2.

The embodiment shown in FIG. 3 includes a load lock chamber 180, or anauxiliary chamber like a buffer station. This chamber 180 is connectedto a side of the processing chamber 100 to allow, for example thesubstrates (also referred to as substrates 60) to be loaded/unloadedfrom the chamber 100. A wafer robot may be positioned in the chamber 180to move the substrate onto the susceptor.

Rotation of the carousel (e.g., the susceptor assembly 140) can becontinuous or discontinuous. In continuous processing, the wafers areconstantly rotating so that they are exposed to each of the injectors inturn. In discontinuous processing, the wafers can be moved to theinjector region and stopped, and then to the region 84 between theinjectors and stopped. For example, the carousel can rotate so that thewafers move from an inter-injector region across the injector (or stopadjacent the injector) and on to the next inter-injector region wherethe carousel can pause again. Pausing between the injectors may providetime for additional processing steps between each layer deposition(e.g., exposure to plasma).

FIG. 4 shows a sector or portion of a gas distribution assembly 220,which may be referred to as an injector unit 122. The injector units 122can be used individually or in combination with other injector units.For example, as shown in FIG. 5, four of the injector units 122 of FIG.4 are combined to form a single gas distribution assembly 220. (Thelines separating the four injector units are not shown for clarity.)While the injector unit 122 of FIG. 4 has both a first reactive gas port125 and a second reactive gas port 135 in addition to purge gas ports155 and vacuum ports 145, an injector unit 122 does not need all ofthese components.

Referring to both FIGS. 4 and 5, a gas distribution assembly 220 inaccordance with one or more embodiment may comprise a plurality ofsectors (or injector units 122) with each sector being identical ordifferent. The gas distribution assembly 220 is positioned within theprocessing chamber and comprises a plurality of elongate gas ports 125,135, 155 and elongate vacuum ports 145 in a front surface 121 of the gasdistribution assembly 220. The plurality of elongate gas ports 125, 135,155 and elongate vacuum ports 145 extend from an area adjacent the innerperipheral edge 123 toward an area adjacent the outer peripheral edge124 of the gas distribution assembly 220. The plurality of gas portsshown include a first reactive gas port 125, a second reactive gas port135, a vacuum port 145 which surrounds each of the first reactive gasports and the second reactive gas ports and a purge gas port 155.

With reference to the embodiments shown in FIG. 4 or 5, when statingthat the ports extend from at least about an inner peripheral region toat least about an outer peripheral region, however, the ports can extendmore than just radially from inner to outer regions. The ports canextend tangentially as vacuum port 145 surrounds reactive gas port 125and reactive gas port 135. In the embodiment shown in FIGS. 4 and 5, thewedge shaped reactive gas ports 125, 135 are surrounded on all edges,including adjacent the inner peripheral region and outer peripheralregion, by a vacuum port 145.

Referring to FIG. 4, as a substrate moves along path 127, each portionof the substrate surface is exposed to the various reactive gases. Tofollow the path 127, the substrate will be exposed to, or “see”, a purgegas port 155, a vacuum port 145, a first reactive gas port 125, a vacuumport 145, a purge gas port 155, a vacuum port 145, a second reactive gasport 135 and a vacuum port 145. Thus, at the end of the path 127 shownin FIG. 4, the substrate has been exposed to gas streams from the firstreactive gas port 125 and the second reactive gas port 135 to form alayer. The injector unit 122 shown makes a quarter circle but could belarger or smaller. The gas distribution assembly 220 shown in FIG. 5 canbe considered a combination of four of the injector units 122 of FIG. 4connected in series.

The injector unit 122 of FIG. 4 shows a gas curtain 150 that separatesthe reactive gases. The term “gas curtain” is used to describe anycombination of gas flows or vacuum that separate reactive gases frommixing. The gas curtain 150 shown in FIG. 4 comprises the portion of thevacuum port 145 next to the first reactive gas port 125, the purge gasport 155 in the middle and a portion of the vacuum port 145 next to thesecond reactive gas port 135. This combination of gas flow and vacuumcan be used to prevent or minimize gas phase reactions of the firstreactive gas and the second reactive gas.

Referring to FIG. 5, the combination of gas flows and vacuum from thegas distribution assembly 220 form a separation into a plurality ofprocessing regions 250. The processing regions are roughly definedaround the individual reactive gas ports 125, 135 with the gas curtain150 between 250. The embodiment shown in FIG. 5 makes up eight separateprocessing regions 250 with eight separate gas curtains 150 between. Aprocessing chamber can have at least two processing region. In someembodiments, there are at least three, four, five, six, seven, eight,nine, 10, 11 or 12 processing regions.

During processing a substrate may be exposed to more than one processingregion 250 at any given time. However, the portions that are exposed tothe different processing regions will have a gas curtain separating thetwo. For example, if the leading edge of a substrate enters a processingregion including the second reactive gas port 135, a middle portion ofthe substrate will be under a gas curtain 150 and the trailing edge ofthe substrate will be in a processing region including the firstreactive gas port 125.

A factory interface 280, which can be, for example, a load lock chamber,is shown connected to the processing chamber 100. A substrate 60 isshown superimposed over the gas distribution assembly 220 to provide aframe of reference. The substrate 60 may often sit on a susceptorassembly to be held near the front surface 121 of the gas distributionassembly 120 (also referred to as a gas distribution plate). Thesubstrate 60 is loaded via the factory interface 280 into the processingchamber 100 onto a substrate support or susceptor assembly (see FIG. 3).The substrate 60 can be shown positioned within a processing regionbecause the substrate is located adjacent the first reactive gas port125 and between two gas curtains 150 a, 150 b. Rotating the substrate 60along path 127 will move the substrate counter-clockwise around theprocessing chamber 100. Thus, the substrate 60 will be exposed to thefirst processing region 250 a through the eighth processing region 250h, including all processing regions between. For each cycle around theprocessing chamber, using the gas distribution assembly shown, thesubstrate 60 will be exposed to four ALD cycles of first reactive gasand second reactive gas.

The conventional ALD sequence in a batch processor, like that of FIG. 5,maintains chemical A and B flow respectively from spatially separatedinjectors with pump/purge section between. The conventional ALD sequencehas a starting and ending pattern which might result in non-uniformityof the deposited film. The inventors have surprisingly discovered that atime based ALD process performed in a spatial ALD batch processingchamber provides a film with higher uniformity. The basic process ofexposure to gas A, no reactive gas, gas B, no reactive gas would be tosweep the substrate under the injectors to saturate the surface withchemical A and B respectively to avoid having a starting and endingpattern form in the film. The inventors have surprisingly found that thetime based approach is especially beneficial when the target filmthickness is thin (e.g., less than 20 ALD cycles), where starting andending pattern have a significant impact on the within wafer uniformityperformance. The inventors have also discovered that the reactionprocess to create SiCN, SiCO and SiCON films, as described herein, couldnot be accomplished with a time-domain process. The amount of timerequired to purge the processing chamber results in the stripping ofmaterial from the substrate surface. The stripping does not happen withthe spatial ALD process described because the time under the gas curtainis short.

Accordingly, embodiments of the disclosure are directed to processingmethods comprising a processing chamber 100 with a plurality ofprocessing regions 250 a-250 h with each processing region separatedfrom an adjacent region by a gas curtain 150. For example, theprocessing chamber shown in FIG. 5. The number of gas curtains andprocessing regions within the processing chamber can be any suitablenumber depending on the arrangement of gas flows. The embodiment shownin FIG. 5 has eight gas curtains 150 and eight processing regions 250a-250 h. The number of gas curtains is generally equal to or greaterthan the number of processing regions. For example, if region 250 a hadno reactive gas flow, but merely served as a loading area, theprocessing chamber would have seven processing regions and eight gascurtains.

A plurality of substrates 60 are positioned on a substrate support, forexample, the susceptor assembly 140 shown FIGS. 1 and 2. The pluralityof substrates 60 are rotated around the processing regions forprocessing. Generally, the gas curtains 150 are engaged (gas flowing andvacuum on) throughout processing including periods when no reactive gasis flowing into the chamber.

A first reactive gas A is flowed into one or more of the processingregions 250 while an inert gas is flowed into any processing region 250which does not have a first reactive gas A flowing into it. For exampleif the first reactive gas is flowing into processing regions 250 bthrough processing region 250 h, an inert gas would be flowing intoprocessing region 250 a. The inert gas can be flowed through the firstreactive gas port 125 or the second reactive gas port 135.

The inert gas flow within the processing regions can be constant orvaried. In some embodiments, the reactive gas is co-flowed with an inertgas. The inert gas will act as a carrier and diluent. Since the amountof reactive gas, relative to the carrier gas, is small, co-flowing maymake balancing the gas pressures between the processing regions easierby decreasing the differences in pressure between adjacent regions.

Accordingly, one or more embodiments of the disclosure are directed toprocessing methods utilizing a batch processing chamber like that shownin FIG. 5. A substrate 60 is placed into the processing chamber whichhas a plurality of processing regions 250, each section separated fromadjacent section by a gas curtain 150. At least a portion of thesubstrate surface is exposed to a first process condition in a firstsection 250 a of the processing chamber. For example, the first processcondition comprises the silicon-containing precursor and an optionalcarrier gas. In the first section 250 a, the first silicon-containingfilm can be formed.

The substrate surface is laterally moved through a gas curtain 150 to asecond section 250 b. Here, the first silicon-containing film is exposedto a second process condition comprising a carbon-containing precursorto form the second silicon-containing film.

The substrate surface is laterally moved with the secondsilicon-containing film through a gas curtain 150 to a third section 250c of the processing chamber. The third section can be either the plasmaexposure or a purge gas region. In the embodiment shown in FIG. 5, thereare eight sections. If there are three process conditions, then a purgesection might be used to geometrically balance the deposition so that acomplete cycle through the processing chamber results in the formationof two layers. Accordingly, the substrate having the secondsilicon-containing film is moved through a gas curtain 150 to either thethird section 250 c or the fourth section 250 d. In the third section250 c or fourth section 250 d, the second silicon-containing film isexposed to plasma to form the silicon-carbon film.

In an embodiment including oxygen exposure, the third section 250 cmight include the oxygen source gas. For example, the secondsilicon-containing film can be exposed to an oxidizing gas in the thirdsection 250 c before moving into the fourth section 250 d.

The substrate surface can then be laterally moved from the fourthsection 250 d through a gas curtain 150 into another region of theprocessing chamber. In the other regions of the processing chamber, thesubstrate surface can be, for example, repeatedly exposed to additionalfirst, second, third and/or fourth process conditions to form a filmwith a predetermined film thickness.

EXAMPLES

Several SiCN films were formed using different plasma gases. Each of thefilms was formed at about 550° C. with a pressure of about 6.5 Torr anda rotation speed of about 6 rpm. Dichlorosilane was flowed into thefirst sections at a flow rate of about 400 sccm. Ethylene diamine wasflowed into the second sections at a flow rate of about 250 sccm. Theplasma formed in the fourth sections was varied as shown in Table 1. Thethird section had a purge gas flow.

TABLE 1 Example Example Example A B C Example D Plasma composition ArAr/N₂ Ar/N₂/NH₃ Ar/H₂ GPC (Å/cycle) 0.458 0.504 0.495 0.271 Refractiveindex 1.996 1.956 1.952 2.01 WERR 0.12 0.20 0.22 0.02

Several SiCN films were formed using different plasma powers. Each ofthe films was formed at about 550° C. with a pressure of about 6.5 Torrand a rotation speed of about 6 rpm. Dichlorosilane was flowed into thefirst sections at a flow rate of about 400 sccm. Ethylene diamine wasflowed into the second sections at a flow rate of about 250 sccm. Theplasma formed in the fourth section was Ar/H₂ mixture (1200/300) and thepower was varied as shown in Table 2. The third section had a purge gasflow.

TABLE 2 Example E Example F Example G Plasma Power 200 W 100 W 50 W GPC(Å/cycle) 0.271 0.233 0.210 Refractive index 2.01 1.99 1.98 Dielectricconstant 5.8 5.0 4.4 WERR .02 .02 .02

Accordingly, some embodiments of the disclosure are directed to SiCNfilms having a refractive index greater than or equal to about 1.950,1.960, 1.970, 1.980, 1.990 or 2.000 and/or a wet etch rate ratio lessthan about 0.25, 0.20, 0.15, 0.10, 0.05 or 0.03. In some embodiments,the SiCN film has a dielectric constant less than or equal to about 5.8,5.6, 5.4, 5.2, 5.0, 4.8, 4.6, 4.5 or 4.4.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or it can be moved from the first chamber to one ormore transfer chambers, and then moved to the separate processingchamber. Accordingly, the processing apparatus may comprise multiplechambers in communication with a transfer station. An apparatus of thissort may be referred to as a “cluster tool” or “clustered system,” andthe like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, degassing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. The details of one suchstaged-vacuum substrate processing apparatus are disclosed in U.S. Pat.No. 5,186,718, entitled “Staged-Vacuum Wafer Processing Apparatus andMethod,” Tepman et al., issued on Feb. 16, 1993. However, the exactarrangement and combination of chambers may be altered for purposes ofperforming specific steps of a process as described herein. Otherprocessing chambers which may be used include, but are not limited to,cyclical layer deposition (CLD), atomic layer deposition (ALD), chemicalvapor deposition (CVD), physical vapor deposition (PVD), etch,pre-clean, chemical clean, thermal treatment such as RTP, plasmanitridation, degas, orientation, hydroxylation and other substrateprocesses. By carrying out processes in a chamber on a cluster tool,surface contamination of the substrate with atmospheric impurities canbe avoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants. According to one or moreembodiments, a purge gas is injected at the exit of the depositionchamber to prevent reactants from moving from the deposition chamber tothe transfer chamber and/or additional processing chamber. Thus, theflow of inert gas forms a curtain at the exit of the chamber.

The substrate can be processed in single substrate deposition chambers,where a single substrate is loaded, processed and unloaded beforeanother substrate is processed. The substrate can also be processed in acontinuous manner, similar to a conveyer system, in which multiplesubstrate are individually loaded into a first part of the chamber, movethrough the chamber and are unloaded from a second part of the chamber.The shape of the chamber and associated conveyer system can form astraight path or curved path. Additionally, the processing chamber maybe a carousel in which multiple substrates are moved about a centralaxis and are exposed to deposition, etch, annealing, cleaning, etc.processes throughout the carousel path.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support andflowing heated or cooled gases to the substrate surface. In someembodiments, the substrate support includes a heater/cooler which can becontrolled to change the substrate temperature conductively. In one ormore embodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discreet steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

In atomic layer deposition type chambers, the substrate can be exposedto the first and second precursors either spatially or temporallyseparated processes. Temporal ALD is a traditional process in which thefirst precursor flows into the chamber to react with the surface. Thefirst precursor is purged from the chamber before flowing the secondprecursor. In spatial ALD, both the first and second precursors aresimultaneously flowed to the chamber but are separated spatially so thatthere is a region between the flows that prevents mixing of theprecursors. In spatial ALD, the substrate is moved relative to the gasdistribution plate, or vice-versa.

In embodiments, where one or more of the parts of the methods takesplace in one chamber, the process may be a spatial ALD process. Althoughone or more of the chemistries described above may not be compatible(i.e., result in reaction other than on the substrate surface and/ordeposit on the chamber), spatial separation ensures that the reagentsare not exposed to each in the gas phase. For example, temporal ALDinvolves the purging the deposition chamber. However, in practice it issometimes not possible to purge all excess reagents out of the chamberbefore flowing in additional regent. Therefore, any leftover reagent inthe chamber may react. With spatial separation, excess reagent does notneed to be purged, and cross-contamination is limited. Furthermore, alot of time can be required to purge a processing chamber, and thereforethroughput can be increased by eliminating the purge step.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A processing method comprising: exposing at leasta portion of a substrate surface to a silicon-containing precursor toform a first silicon-containing film; exposing the firstsilicon-containing film to a carbon-containing precursor to form asecond silicon-containing film, the second silicon-containing filmcomprising carbon; and exposing the second silicon-containing film to aplasma to form a silicon-carbon film.
 2. The processing method of claim1, wherein the silicon-containing precursor comprises silicon halide. 3.The processing method of claim 2, wherein the silicon-containingprecursor consists essentially of silicon halide.
 4. The processingmethod of claim 1, wherein the carbon-containing precursor comprises acompound having carbon and nitrogen atoms.
 5. The processing method ofclaim 4, wherein the carbon-containing precursor comprises substantiallyno oxygen atoms.
 6. The processing method of claim 4, wherein thecarbon-containing precursor comprises one or more of an alkylamine,diamine, polyamine or a cyclic amine.
 7. The processing method of claim1, wherein the carbon-containing precursor comprises a compound havingcarbon and oxygen atoms.
 8. The processing method of claim 7, whereinthe carbon-containing precursor comprises substantially no nitrogenatoms.
 9. The processing method of claim 7, wherein thecarbon-containing precursor comprises one or more of CO₂, an alcoholand/or an ether.
 10. The processing method of claim 1, wherein thecarbon-containing precursor comprises carbon, oxygen and nitrogen atoms.11. The processing method of claim 10, wherein the carbon-containingprecursor comprises one or more of an alkylamino-alcohol or a mixture ofcompounds having carbon and nitrogen atoms or carbon and oxygen atoms.12. The processing method of claim 1, wherein the method is performed ata temperature in the range of about 200° C. to about 650° C.
 13. Theprocessing method of claim 1, further comprising exposing the secondsilicon-containing film to an oxygen source prior to exposure to theplasma to form a silicon-carbon-oxygen film.
 14. The processing methodof claim 1, wherein the plasma comprises at least one inert species andan oxygen species and the silicon-carbon film further comprises oxygen.15. The processing method of claim 1, wherein the plasma comprises atleast one inert species and a nitrogen-containing precursor and thesilicon-carbon film further comprises nitrogen.
 16. A processing methodcomprising exposing a substrate surface to at least two depositioncycles, each deposition cycle comprising: exposing at least a portion ofthe substrate surface to a silicon-containing precursor to form a firstsilicon-containing film; exposing the silicon-containing film to acarbon-containing precursor consisting essentially of carbon andnitrogen atoms to form a second silicon-containing film; and exposingthe second silicon-containing film to a plasma to form a siliconcarbonitride film.
 17. The processing method of claim 16, wherein thesilicon-containing precursor comprises a silicon halide, and thecarbon-containing precursor consists essentially of ethylenediamine. 18.The method of claim 17, wherein the silicon carbonitride film has a wetetch rate ratio in dilute HF relative to a thermal silicon oxide film ofless than about 0.5.
 19. The method of claim 16, wherein one or more ofthe carbon-containing precursor or the plasma further comprises anoxygen-containing species.
 20. A processing method comprising: placing asubstrate having a substrate surface into a processing chambercomprising a plurality of sections, each section separated from adjacentsections by a gas curtain; exposing at least a portion of the substratesurface to a first process condition in a first section of theprocessing chamber, the first process condition comprising asilicon-containing precursor to form a first silicon-containing film;laterally moving the substrate surface through a gas curtain to a secondsection of the processing chamber; exposing the first silicon-containingfilm to a carbon-containing precursor to form a secondsilicon-containing film, the carbon-containing precursor consistingessentially of carbon and nitrogen atoms to form a secondsilicon-containing film; laterally moving the substrate surface with thesecond silicon-containing film through at least one gas curtain to athird section or fourth section of the processing chamber; exposing thesecond silicon-containing film to a plasma comprising an inert gas and,optionally, one or more of hydrogen, nitrogen and oxygen containingspecies to form a silicon carbonitride or silicon oxycarbonitride film;and laterally moving the substrate surface from the third section orfourth section of the processing chamber through a gas curtain; andrepeating exposure to the first section, second section and thirdsection or fourth section including lateral movement of the substratesurface to form a silicon carbonitride or silicon oxycarbonitride filmof a predetermined thickness.